Hiroe - On 3.1 - you are modifying the Average program that is found in your book (page 161). The actual code is found on the book CD under examples (somewhere). I focused on modifying the code so that when someone enters a 0 (zero), the program ends, instead of going through the rest of the program (doing the division, etc).
You don't state your problem with #3.2.
On 3.5, I didn't use "StringTokenizer". Instead, focus on using a while loop, some sort of counting method, .charAt() and .length() in your code.
Hope this helps.
Loreta Anderson
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Life - no argument to win, just understanding to be earned.